1. Field of Invention
This invention relates generally to three-dimensional shape representations and more particularly to applying a rotational transformation to a portion of a representation of an appliance for a living body.
2. Description of Related Art
Prostheses, orthoses, and other support appliances are commonly produced from three-dimensional representations of a body part of a human or an animal. The three-dimensional representation may then be manipulated on a computer using a three-dimensional shape editing program to produce a modified representation of the body part. The modified representation may be used to generate instructions for controlling a carving machine that is configured to directly produce an appliance, or to produce a mold for making an appliance, for example. An orthosis is an appliance that is applied externally to a body part to correct deformity, improve function, or relieve symptoms of a disease by supporting or assisting the musculo-neuro-skeletal system. A prosthesis is an appliance that replaces a missing body part. Other appliances such as supporting seats or standing shells for supporting the body of a person having limited mobility may also be produced from modified representations of body parts.
The three-dimensional representation of the body part may be produced using a non-contact optical scanner that images the body part with a high level of accuracy. The scanner may include a laser for illuminating the body part with structured light and a video camera for capturing images of the illuminated body part. The captured images may then be processed to extract coordinates of the surface of the body part, which may be used as input coordinates to a computer for producing a preliminary three-dimensional representation of the appliance. In cases where scanned input coordinates are available for the specific patient for whom the appliance is to be produced, it is common to make certain modifications to the scanned coordinates to provide compression and/or relief such that the final appliance provides the required support where needed while being sufficiently comfortable for the patient. In other cases, the preliminary three-dimensional representation of the appliance may be provided from a library of body parts, which may require modifications in size and shape to provide the required support and comfort for the patient.
There remains a need for methods and apparatus for modifying a set of input coordinates representing a preliminary shape of an appliance to produce a modified set of coordinates representing a final shape of the appliance.